In the past paper was printed with primarily water or oil based inks which were satisfactorily removed by conventional deinking procedures. In conventional deinking procedures, paper is mechanically pulped and contacted with an aqueous medium containing a deinking chemical. The pulping and presence of the deinking chemical resulted in a separation of the ink from the pulp fibers and the dispersed ink is then separated from the pulp fibers by washing or flotation processes.
Today, increasing amounts of printed paper are generated from electrophotographic processes such as xerography and non-impact printing processes such as laser and ink-jet printing. Processes and deinking chemicals capable of deinking these types of printed paper are very complex and are capital intensive. In addition, multiple steps are required for debris removal and actual ink removal. Generally, ink removal procedures involve washing, flotation, forward cleaning and high consistency dispersion to reach the level of speck removal and brightness required in the deinked pulp to create recyclable paper.
U.S. Pat. Nos. 4,666,558, 4,618,400 and 4,561,933 to Wood et al. are representative of processes involving washing and flotation procedures to deink wastepaper. However, these methods employ deinking compositions containing alcohol ethoxylate surfactants that are limited to deinking either newsprint or xerographic printed paper.
U.S. Pat. Nos. 4,231,841 and 4,360,439 to Calmanti et al disclose chemical compositions used in deinking processes consisting of a mixture of five components which are respectively, a salt of a fatty acid, ethoxylated and/or propoxylated surfactants, sulphonates or sulphates, sodium carboxymethylcellulose and an alkali inorganic salt. The deinking compositions of Calmanti '841 and '439, however, also have limited capabilities and are used in the washing process for deinking news and magazine printed wastepaper.
Thus the present practice, employing known deinking processes and chemicals, has problems in deinking a wide variety of impact and non-impact printed paper. The inventions and practice to date, deal with deinking chemicals having limitations to specific inks and deinking processes which require complex and expensive procedures to obtain recyclable grade paper.
There is a need in the art for deinking chemicals and processes which cause removal of all types of inks, both impact and nonimpact, for all grades of paper. This invention is directed to the provision of such a deinking chemical and related process which has wide range applications in creating recyclable grade paper. It will be appreciated that advantage over conventional deinking chemicals would be obtained by providing an effective and efficient deinking composition capable of deinking all types of printed paper.
Accordingly, it is a broad object of the invention to provide a deinking composition and related process for the removal of all types of inks, both impact and nonimpact, from wood containing and wood free grades of paper.
A more specific object of the invention is to provide a deinking composition comprising a mixture of one or more solvents and nonionic and anionic surfactants for the removal of all types of inks, both impact and nonimpact, from wood containing and wood free grade of paper.
Another object of the invention is to provide a deinking composition capable of both dispersion and collection of all types of inks, both impact and nonimpact, from wood containing and wood free grade of paper.
Another object of the invention is to provide a low cost deinking process and apparatus that effectively and efficiently removes ink without using a high concentration of expensive deinking chemicals.
A further specific object of the invention is to provide a recycled paper product made by the deinking process of the invention from impact and/or nonimpact printed paper.